Nickel base alloy

ABSTRACT

The present invention contemplates nickel-base alloys consisting in percent by weight essentially of about 0.1% to about 0.25% carbon, about 9% chromium, about 0.75% to about 2% titanium, about 5% to about 6.25% aluminum, about 8% to about 12% cobalt, about 8% to about 12% tungsten, about 0.8% to about 2.5% hafnium, about 0.002% to about 0.2% boron, up to about 0.15% zirconium and about 2.5% tantalum, with the balance being essentially nickel.

United States Patent [1 1 Hockin et a1.

[ 1 Oct. 16, 1973 1 NICKEL BASE ALLOY [75] Inventors: John Hockin; CarlH. Lund, both of Arlington Heights; Michael J. Woulds, Shaumburg, all of 111.

[73] Assignee: Martin Marietta Corporation, New

York, N.Y.

221 Filed: Dec. 17 1970 21 Appl. No.: 99,232

Related US. Application Data [63] Continuation-impart of Ser. No. 841,505, July 14,

1969, abandoned.

[52] US. Cl. 75/171, 148/325 [51] Int, Cl..... C22c 19/00 [58] Field of Search 75/171, 170; 148/32,

[56] References Cited UNITED STATES PATENTS 3,479,157 11/1969 Richards et al 75/171 Primary Examiner-Richard 0. Dean AttorneyJohn A. Crowley, Jr.

[57] ABSTRACT 3 Claims, No Drawings C 0.040.35% Ti 0.6-5%

Cr 713% Al 4.56.7% Co 7-13% Al+Ti 6.5-10.5% W up to 14% B 0.002-0.2% Mo up to 7% Zr up to 0.15% Ta up to 5% Cb up to 2.2% Hf 0.75% V up to 1.1%

Ni Balance essentially Particular alloys within this range can possess compositions in percent by weight, as disclosed in US. application Ser. No. 841 ,505, now abandoned, as follows:

A B C 0.15 0.15 Cr 9 9 M0 2.5 Ti 1.5 1.5 A1 5.5 5.5 Co 10 10 W 10 10 Hf 1.5 2.5 Ta 1.5 1.5 Zr 0.05 0.05 B 0.015 0.015 Ni Bal. E Bal. E.

Bal. E. Balance Essentially and includes small amounts of unavoidable impurities and incidental elements 1 It is disclosed in application Ser. -No. 841,505, now abandoned, that lowering of molybdenum from 2.5

percent in alloy A to 0 percent as in alloy B coupled with an increase in hafnium content from 1.5 percent to 2.5 percent results in an alloy having highly advantageous impact resistance characteristics. Following this approach further, it has now been discovered that by maintaining the ingredients in the general type or nickel-base alloy, as exemplified by alloy B, within very restricted ranges a highly advantageous commercial alloy can be provided.

It is an object of the present invention to provide a highly advantageous, commercial, nickel-base alloy.

, Other objects and advantages will become apparent from the following description.

Generally speaking, the present invention contemplates nickel-base alloys within the ambit of the alloy range in US. application Ser. No. 841,505, now abandoned, consisting, in percent by weight, essentially of about 0.1% to about 0.25% carbon, about 7.5% to about 10.7% chromium, about 0.75% to about 2% titanium, about 5% to about 6.25% aluminum, about 8% to about 12% cobalt about 8% to about 12% tungsten, about 0.8% to about 2.5% hafnium, about 0.002% to about 0.2% boron, up to about 0.15% zirconium, about 2.5% tantalum, with the balance being essentially nickel. Advantageously, the tantalum content of the alloys is about 2.25% to about 2.75% and the total of the aluminum plus titanium percentages is about 7%.

An illustrative alloy of the present invention contains, in nominal percentages, 0.15% carbon, 9% chromium, 1.5% titanium, 5.5% aluminum, 10% cobalt,

10% tungsten, 1.5% hafnium, 2.5% tantalum, 0.01% boron, 0.1% zirconium, balance essentially nickel. When melted and cast under vacuum into gas turbine structures, such as gas turbine blades the alloy of the present invention produces excellent parts characterized by a high combination of the characteristics of impact resistance, high and intermediate temperature strength, reproducibility, resistance to thermal fatigue, stability to long term exposure to high temperatures and the like.

The following tables contain data obtained on representative samples machined from turbine blades which show the utility of the alloy of the present invention with respect to various mechanical characteristics of engineering significance.

When tested at 1,900F. (1,038C.) under a load of 15.68 thousands of pounds per square inch (k.s.i.) [1102.3 kilograms per square centimeter (kg/cm a substantial number of samples exhibited the lives-torupture, percents elongation and percents reduction of area as set forth in Table 1.

The data in Table I shows that in actual turbine engine hardware form, the alloy of the present invention has substantial utility at temperatures as high as 1,900F. and higher. Similar data with respect to tests conducted at 1,400F. (760C.) under a load of 101.8 k.s.i. [7,156.5 kg/cm] is set forth in Table 11.

TABLE II Life-to-Rupture longation duction of Area The data in Table 11 shows that in actual turbine engine hardware form, the alloy of the present invention has substantial utility at intermediate temperatures about 1,400F. as well as at higher temperatures of up to and beyond 1,900F.

Table 111 shows the approximate level of stress at various temperatures which will result in about hours of'life of test samples machinedfrom cast turbine blades made of the alloy of the present invention.

TABLE 111 Temperature Stress for 100 hours life F. k.s.i. kg/cm 1292 700 116.7 8200 1382 750 103.0 7250 1472 800 82.8 5820 1562 850 62.7 4415 1652 900 44.7. 3140 1742 950 34.7 2440 1832 1000 21.3 1500 1922 1050 13.4 943 The data in Table 111 show that the alloy of thepresent.

invention is a highly advantageous," commercially acceptable alloy especially in view of the fact that the alloy of the present invention exhibits high impact strengths of the order of about 30 foot-pounds or higher, which impact strengths are relatively unaffected by exposure to high temperature for extended periods of time. The alloy of the present invention is also characterized by high resistance to thermal fatigue, high reproducibility from heat to heat and a high combination of characteristics of engineering significance when tested from room temperature up to 1,900F. and higher.

Specific examples of alloys within the ambit of the present invention are set forth (in percent by weight) in Table. IV.

Bal. E. Balance essentially The alloys of the present invention are advantageously melted and cast under vacuum using investment casting techniques. Those skilled in the art will appreciate that the alloys of the invention can contain small amounts of incidental elements and impurities along with and encompassed within the term balance nickel. Such impurities and incidental elements should be maintained at as low a level practical considering the needs of commercial production. The alloys of the present invention, while being particularly adapted for use as cast gas turbine components, such as turbine blades and the like, can be used also with advantage in any area of utility where strength at elevated temperatures is a necessary criterion.

While the present invention has been described in conjunction with advantageous embodiments, those skilled in the art will recognize that modifications and variations may be resorted to without departing from the spirit and scope of the invention. Such modifications and variations are considered to be within the purview and scope of the invention.

We claim:

1. A nickel-base alloy consisting essentially in percent by weight of about 0.1% to about 0.25% carbon, about 7.5% to about 10.7% chromium, about 0.75% to about 2% titanium, about 5% to about 6.25% aluminum, the total of the percentages of aluminum plus titanium being at least 6.5%, about 8% to about 12% cobalt, about 8% to about 12% tungsten, about 0.8% to about 2.5hafnium, about 0.002% to about0.2% boron, up to about 0.15% zirconium, about 2.25% to about 2.75% tantalum, with the balance being essentially nickel.

2. An alloy as in claim 1 wherein the tantalum content is about 2.5 percent.

3. An alloy as in claim 1 wherein the percent aluminum plus the percent titanium is about 7 percent.

UNmm STATES PATENT OFFECE CERTlFlCATE OF CORRECTlON Patent: No. 3,765,879 Dated Oct. 16, 1973 Inventor g John Hockin et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 43, "or" should be of line 58, after "cobalt" the comma is omitted.

Column 2, line 54, in TABLE 11, first column, "136. 0 should be 136.6

Colunm 4, line 32 2. 5hainium" should be 2. 5% hafnium Signed and sealed this 12th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN ing Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 u.s. sovsnnuznr ram-nus OFFICE: ls" o-ass-su. 

2. An alloy as in claim 1 wherein the tantalum content is about 2.5 percent.
 3. An alloy as in claim 1 wherein the percent aluminum plus the percent titanium is about 7 percent. 